Alcohol and drug use during adolescence contributes significantly to unsafe sexual practices, school failure, delinquency, and adverse health outcomes. Latinos, a rapidly growing ethnic population, are at especially high risk for substance use and risky health behaviors. Bilingual and more acculturated Latino adolescents appear to be at greater risk for AOD use than monolingual Spanish-speaking adolescents. Treatment of adolescent substance abusers (ASAbusers) includes self-monitoring of AOD use behaviors. However, retrospective reports about AOD-related behaviors are subject to recall errors, biases, and faked compliance. In addition, the gold standard for monitoring outpatient abstinence, the urine toxicology screen, is cumbersome and vulnerable to manipulation. This is a proposal for the testing of the feasibility and acceptability of ecological momentary assessment data collection of AOD use behaviors using cellphone and text-messaging technology (CEMA). The goals of the study are to develop a prototype CEMA and to test the psychometric correspondence and criterion validity of CEMA against standard assessment procedures (retrospective self-reports and urine toxicology screens, respectively). The research will entail two phases. The aims for Phase 1 are to a) assess the acceptability of the CEMA monitoring content for ASAbusers in order to establish data collection parameters;b) assess and optimize the acceptability of the CEMA algorithm for treatment administrators, counselors, and Latino parents. In particular, the ethical challenges of CEMA will be examined and a protocol for reporting dangerous behaviors will be created;c) field test a CEMA prototype with treatment program graduates and examine their adherence to different sampling strategies (event-based, daily, random, or combination). Phase 2 will consist of a pilot test of the protocol with 30 Latino ASAbusers for one month. From the data collected, we will examine a) the acceptability of and compliance with CEMA protocol;b) the psychometric correspondence of CEMA monitoring by comparing the CEMA reports from the different sampling strategies to each other and to retrospective self-reports;c) the criterion validity of CEMA monitoring by comparing CEMA reports of AOD use with urine toxicology results. PUBLIC HEALTH RELEVANCE: Substance abuse among American youths continues to pose a serious public health concern, especially among Latinos, who are a rapidly growing ethnic population disproportionately affected by alcohol or drug (AOD) use and HIV/AIDS. The demand for substance abuse treatment for adolescents is expected to rise, and current methods of monitoring abstinence are limited by cost and compliance issues. This study aims to develop a novel assessment tool, examine its feasibility and acceptability among relevant constituencies, and test its psychometric correspondence and criterion validity against standard assessment procedures;the findings from this study will contribute to our understanding of adolescent substance use and the development of new assessment tools for this understudied population of substance abusers.